Plywood Calculator
Works for plywood and OSB sheathing on floors, walls and roofs. Enter the area you're covering and the sheet size to get the number of sheets, with a waste allowance for cuts.
Results
How the plywood calculator works
Sheet goods are estimated by area. The calculator takes the surface you're covering, adds a waste allowance for the offcuts you can't reuse, and divides by the area of one sheet — a standard 4 × 8 sheet is 32 square feet — then rounds up to whole sheets.
Formula: area × (1 + waste%) ÷ sheet area = sheets (rounded up)
| Area | 4×8 sheets |
|---|---|
| 100 sq ft | 4 |
| 200 sq ft | 7 |
| 400 sq ft | 14 |
| 1,000 sq ft | 35 |
Plywood and OSB tips
- Common thicknesses: ⅞" or ¾" for subfloors, ½" or ⅝" for wall and roof sheathing, ¼" for cabinet backs and underlayment. Thickness doesn't change the sheet count — only the area does.
- Stagger the joints from row to row like brickwork so no seam runs the full length; it's stronger and flatter.
- Leave a ⅛" gap at sheet edges on subfloors and sheathing — wood swells with humidity, and tight sheets buckle.
- OSB and plywood are interchangeable for most sheathing and subfloor jobs; plywood handles repeated wetting a little better, OSB usually costs less.
Frequently asked questions
How many sheets of plywood do I need for 200 square feet?
A 4 × 8 sheet covers 32 square feet, so 200 sq ft is about 7 sheets once you add 10% for waste (200 ÷ 32 = 6.25, rounded up after waste to 7).
How do I calculate plywood sheets?
Multiply length by width for the area, add about 10% for cuts and waste, then divide by 32 (the square footage of a 4×8 sheet) and round up to whole sheets.
How many square feet is a 4x8 sheet of plywood?
Exactly 32 square feet — 4 feet by 8 feet. A 4×9 sheet is 36 sq ft and a 4×10 sheet is 40 sq ft.
Is OSB or plywood better for a subfloor?
Both are code-approved for subfloors and estimate the same way. Plywood dries faster and holds fasteners slightly better if it gets wet; OSB is more uniform and usually cheaper. Either works with proper gapping and fastening.